1. Field of the Invention
This invention relates generally to transmitters, and more specifically, to an internal adjustable capacitor for a transmitter system which will allow a user to easily adjust and/or set the centerpoint of the transmitter oscillator frequency.
2. Background of the Invention
For transmitter and receiving devices such as a remote activated garage door openers or remote activated car alarms, a transmitter will send a signal at a desired frequency to the receiver. The transmitter oscillator frequency must match the setting in the receiver. If the frequency of the transmitter is a little off, the receiver/transmitter devices will not operate or will not operate at long distances.
Presently, most RF transmitters have an external capacitor which is coupled to the RF transmitter. The external capacitor is a tunable capacitor which is used to set the centerpoint of the transmitter oscillator frequency. The problem with external capacitors is that they are expensive to implement. This is due to the fact that each capacitor has to be individually trimmed to the desired setting for each transmitter. Furthermore, once the external capacitor is set, the capacitor is generally sealed in wax or some other substance. Thus, once set, the external capacitor is difficult to adjust and retune if the transmitter oscillator frequency has shifted or was not properly set at manufacture.
Therefore, a need existed to provide an improved transmitter/receiver system. The improved transmitter/receiver system will have a transmitter system which is capable of adjusting and setting the transmitter oscillator frequency. The transmitter system will have a tunable internal capacitor for setting the centerpoint of the transmitter oscillator frequency.